Talk:R/K selection theory

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"Lost importance"
In the opening of the article it's stated that the theory has "lost importance". This is vague and overly general and worded as opinion. Yes, newer theories have expanded or reformed r/k (actually, most have just said the same thing while changing the name because r/k was labelled "racist" via EO and Rushton). As of May 2012 we are still learning r/k selection in the UC system in California - arguably the top public university system in the world, especially in the biological sciences. Surely there's a better way to explain that expansions of earlier r/k selection theory have appeared rather than calling it "unimportant". It's still one of the foundational topics in organismal biology. — Preceding unsigned comment added by 207.233.120.5 (talk) 23:45, 22 May 2012 (UTC)

I agree. r/K is a foundational concept of biology, the same as supply and demand is in economics. There may well have been more elaborate theories advanced, and thought might have moved beyond r/K, but r/K has not "lost importance" as this article seems to strongly suggest. Issue313 (talk) 17:22, 15 December 2013 (UTC)]

I agree too. As much as I am not a fan, the theory is still very actively and explicitly used in ecology.Kyle MoJo (talk) 05:16, 14 December 2018 (UTC)

J. Philipe Rushton
Just wondering if we need to mention Rushton here? While I can see that it's important for his article to link to this one, it's not obvious that the reverse is necessary. Especially as his work is described as pseudoscience here. Anyway, just thought that it might be better not to burden a science page with not-entirely-appropriate links. Anyone care to comment? --Plumbago 18:16, 9 January 2006 (UTC)


 * I may be over-compensating for my POV here, but... I suppose his theories *are* notable, in the sense of being a popular-press commented upon application of r/K selection theory.  In that case, maybe, if that article does a good job of describing why it is thought to be pseudo-science, it might be of some honest pedagogical value to direct readers there.  I havn't read that article carefully (and don't really look to have much time to such a task), but I would feel a bit like a censor if I were to delete the link.  I have a couple of comments from a review of Rushton's book by D.P. Barash published in journal Animal Behaviour (vol 49, pp1131-1133) which may serve as an indication of the main-stream biologists view of the theory. "...Rushton argues at length for what he calls the 'principle of aggregation', which in his hands, means the pious hope that by combining numerous little turds of variously tainted data, one can obtain a valuable result; but in fact, the outcome is merely a larger than average pile of shit".  "Bad science and virulent racial prejudice drip like pus from nearly every page of this despicable book".  The review does delve into specific failings of his evidence in support of specific claims and is worth reading by anyone mulling-over Rushton's theory. Pete.Hurd 21:42, 9 January 2006 (UTC)


 * Nice review! I'll have a look at that one (assuming our library's up to the task).  As for censorship, yes, I am worried that my suggestion is tantamount to that.  So I think the reference stays for now.  I was originally thinking of removing the reference a) because it's irrelevant to r/K selection as a concept, and b) because, on the whole, my gut feeling is not to give any extra platform space to the likes of Rushton.  Anyway, thanks for replying.  Cheers, --Plumbago 09:04, 10 January 2006 (UTC)


 * Went looking at the reference to r/K selection theory in Race, Evolution and Behavior, J. Philippe Rushton's controversial application of this theory to different human races, and could find none, so have deleted it as marginal to the topic John D. Croft 02:40, 14 November 2007 (UTC)


 * Found it in 3 minutes on page 34 of Ruston's book here Mike Young (talk) 19:56, 16 April 2008 (UTC)


 * Even if it's notable enough to be included, referring to it as "Scientific Racism" violates Wikipedia's NPOV policy. According to the standards described there, Rushton's viewpoint would not be considered "pseudoscience", since it is held by a significant minority of geneticists and psychologists, including some who are very highly-regarded (Jensen, Watson, Wilson, Gottfredson, etc.) and is also covered by numerous papers in mainstream peer-reviewed journals.  Under Wikipedia's policy, these are the only standards by which the distinction between science and pseudoscience can be judged.  I'm going to edit the article to fix the NPOV issue; please don't change it back without discussing it here first. Captain Occam (talk) 17:02, 21 June 2009 (UTC)

Merge (February 2006)
Rather than have two separate forums for discussion, can we stick to Talk:R-K Life History Theory? I've started things off there. Cheers, --Plumbago 15:41, 24 February 2006 (UTC)


 * Merged and redirected R-K Life History Theory to here. Have expanded it's portion on E. O. Wilson in this article.  --Plumbago 09:38, 1 March 2006 (UTC)


 * P.S. Copied my discussion on Talk:R-K Life History Theory to below :


 * This article is much more of a stub than R/K selection theory so should probably be merged into it. That said, it doesn't really contain anything extra, so a redirect might be better.  The one extra thing it does introduce is attributing r-/K-selection to E. O. Wilson.  I've had a quick check and apparently it stems back to a book by Robert MacArthur and E.O. Wilson from the late 1960s ("The Theory of Island Biogeography"), which in turn stems from a joint paper of their's from 1963.  If no-one objects, I'll re-direct this article as suggested, and add this information about MacArthur and Wilson to R/K selection theory.  Cheers, --Plumbago 10:12, 24 February 2006 (UTC)


 * I've just tracked down the 1963 paper, but it contains nothing about r/K. It's possible that the book does, but I've not got access to that to check.  Anyone care to clarify this?  --Plumbago 10:23, 24 February 2006 (UTC)


 * Having now (finally) looked at Pianka (1970), it references MacArthur & Wilson's 1967 book as the source of r and K selection. I'll amend the R/K selection theory article appropriately, and merge this one into it.  There's a snippet of the Pianka article available here.  Cheers, --Plumbago 09:26, 1 March 2006 (UTC)


 * I suggest that the Pianka reference also go into that second sentence along with the MacArthur & Wilson book. Pianka seems to be the classic citation, even if it is not the original source for the term.  Cheers. Pete.Hurd 16:33, 1 March 2006 (UTC)


 * Fair point. Maybe something like "... and was extended by ..."?  --Plumbago 16:47, 1 March 2006 (UTC)

RV expansion of Rushton's work explained
Rushton's work is very much outside the mainstream, and to present it without presenting the opposing view is tantamount to endorsing a POV. His theories, and the counter arguments, are well presented elsewhere. An uncritical presentation of his views here does not add to the understanding of r/K selection, and is intellectual dishonesty. Pete.Hurd 19:08, 6 May 2006 (UTC)


 * It's your job to add in the counterarguments, not to delete information you don't like.  His work is certainly relevant since it is a notable application of r/K theory that has received widespread attention.  What I wrote is cited and factual.  Your blurb stating that it is rejected by "most biologists" is not.  Dd2 20:44, 6 May 2006 (UTC)


 * No, it's not "my job" to add the counter arguments. You want to propagandize racist pseudoscience, fine.  I'm not going to waste my time cutting and pasting the rebuttals from other pages into this one to "debate" your position.  That's not how NPOV is supposed to work, as a back and forth propaganda battle.  If you want to add coverage of this topic, then you should do it with intellectual honesty, and you should do it on the appropriate page. Pete.Hurd 21:33, 6 May 2006 (UTC)


 * Re: Dd2 - It's certainly not a notable addition to r/K theory. It's a gross misapplication at best.  Keep it on Rushton's page.  There's enough about it here already.  r/K is useful in proper ecology, it doesn't need tainting with Rushton's pseudoscience.  A mention of him here is plenty enough.  --Plumbago 08:11, 7 May 2006 (UTC)


 * I agree with you. But Dd2 is right that the "most biologists" qualification is inappropriate per WP:WEASEL. bcasterline t 12:14, 7 May 2006 (UTC)


 * Hi again. Dd2 - your new revision is fine by me.  Thanks for responding to our concerns.  Cheers, --Plumbago 08:36, 8 May 2006 (UTC)

Related to this: editors may wish to note that I nominated Rushton's ordering of the human races for deletion for reasons explained on the article's AFD notice. Pete.Hurd 14:57, 8 May 2006 (UTC)

Adaptive capacity
I've removed the following from the article (but copied it here, and over at Adaptive Capacity). I'm not convinced that it helps articulate the general r/K theory. It seems to me that the concepts of r/K are used in Adaptive Capacity analogously to how they are used in ecology. Certainly the text below is unclear and confusing (and needs copyediting). I've moved adaptive capacity to a "See also" point. Not least because explaining the relevance of r/K for adaptive capacity might be best done there.


 * The Resilience Alliance, as illustrated by the work of C. S. Holling and L. H. Gunderson, shows how the logistic curve of the R phase positive feedback, becoming replaced by the K negative feedback strategy is an important part of adaptive capacity which is important in the survival of ecosystems and human social institutions. The R strategy is associated with situations of low complexity, high resilience, and growing potential.  K strategies are associated with situations of high complexity, high potential and high resilience, but if the perturbations exceed certain limits, adaptive capactity may be exceeded and the system collapse into another so-called Omega state, of low potential, low complexity and low resilience.


 * Gunderson, L.H. and C.S. Holling, editors. Panarchy: Understanding Transformations in Human and Natural Systems. Island Press, Washington.

Of course, I could just be being dense, and haven't understood the relevance of the above! Cheers, --Plumbago 17:33, 9 November 2006 (UTC)

Plumbago, r and K phases are important in the work of the resiliance alliance, and are being widely applied throughout the Applied Environmental Assessment and Monitoring (AEAM) field at present. For this reason I added the section on Adaptive Capacity. I feel it should be included. John D. Croft (talk) 18:38, 23 March 2009 (UTC)


 * Hi John. I'm still rather unclear about how exactly these ecological concepts apply to social systems.  My feeling is that r/K is just being used in adaptive capacity by way of analogy.  But that's just a feeling.  Either way, I'm not convinced that we need to get into a big description of it here.  I'd favour expanding the text about r/K over at adaptive capacity (if anywhere), and perhaps adding it as a "see also" link here.  Because it all seems rather analogous to me, I'd be reluctant to complicate the article here.  Cheers, --P LUMBAGO  11:03, 25 March 2009 (UTC)


 * That said, re-reading adaptive capacity, I guess I can kind-of see how it ties in with ecological processes. My eye was just drawn to the portions of that article on social systems!  Anyway, would adaptive capacity fit into the section on "In ecological succession"?  It seems to have some bearing on climax community.  Cheers, --P LUMBAGO  11:07, 25 March 2009 (UTC)

Removing No Citations label
Should we remove the no citations label now. In fact I find it reasonably well referenced/John D. Croft (talk) 18:38, 23 March 2009 (UTC)

Failed Search
I failed in my search for exactly this page when I entered "r/k". It wasn't in the first ten pages of results, presumably because the search engine ignores forward slashes. I found this page later by accident (while reading about semelparity on the reproduction page). The page should havebeen in the results, can you think of anything that can be done about that? -seth 189.162.17.16 05:12, 20 July 2007 (UTC)


 * A redirect at r/K to here would resolve this. I'll do this now.  --Plumbago 07:09, 20 July 2007 (UTC)

"Bio-sexuality"?
I've removed the following statement from the article:
 * "The bio-sexuality of men tend to be r strategists, women tend more towards a K strategy."

Firstly, it's too human-specific - the purported r/K-strategist traits of men/women apply equally to other organisms (furthermore, since stable reproductive pairs of child-rearing humans are not uncommon, humans may not be a good example). Secondly, r/K is usually viewed as interspecific rather than intergender, but if there's a reliable source (scientific literature) to back this use that'd be great. Certainly, there's something to the idea that different strategies suit different genders, but my feeling is that we need good sources before inserting potentially contentious about human psychology into an article on ecology (c.f. J. Philippe Rushton). If it's original research, while it shouldn't be here, it might well make for a interesting paper! :-) Cheers, --Plumbago 16:33, 26 July 2007 (UTC)


 * I've just removed this again. Please supply some sources for this.  Or at least discuss it here.  Unsourced, it seems just like original research to me (which is only a criticism in that it can't be included here).  Cheers, --Plumbago 07:48, 3 October 2007 (UTC)


 * Sounds like a reference to Bateman's principle and the whole Trivers Parental investment shtick. If there are references in the literature explicitly relating the ideas, then they shouldn't be hard to dig up, but the one sentence standing alone doesn't do a very good job of explaining the idea... Pete.Hurd 13:55, 3 October 2007 (UTC)


 * Ah-ha. Thanks Pete, that's the kind of information that I was looking for to start things off.  I note, however, that the article on Bateman's principle doesn't draw any parallels with r/K selection.  Unless we can find a good source for the link between the two that you mention, we're probably still in OR territory.  If a source can't be found, then that confirms the OR tag and perhaps we all need to collaborate on a paper on it!  ;-)  Cheers, --Plumbago 15:14, 3 October 2007 (UTC)


 * Without a source, applying r/K to gender (esp. human gender) is an analogy at best -- and one with wide-ranging implications at that, making any such comment fall into the realm of original research. It's an interesting idea; unfortunately, it's hardly true unless one insists on assuming traditionalist views of human sexuality. Plenty of males are K-selected; just as many women are r-selected. Even that observation hardly suffices, however, since we as a species have long replaced ecological pressure with sociological ones and this selection theory only makes sense when applied to an entire population anyway. --Richardpaez —Preceding unsigned comment added by 173.170.88.238 (talk) 10:46, 3 June 2009 (UTC)

Controversy not reflected here
This article seems to me misleading. r/K selection became highly controversial as early as the 1970's, and was long ago abandoned by most of those doing research in the evolution of life histories. If nothing else, see the review by Stearns in Ann. Rev. Ecol. Syst.

There's certainly nothing wrong with discussing the theory, but since this is a work that will mainly be consulted by those outside of research in evolutionary biology, I don't think it's a good idea to represent the theory as one that's generally agreed upon. That's just not the case.

I've noticed that lately discussions of r/K selection have begun to appear in places like this, or in textbooks. Obviously you needn't agree with the many criticisms of the theory, but I do think it's misleading not to mention them. An interesting and useful article might address the history of the idea -- its life, death, and recent resurrection outside the research arena -- and reasons for that.

Gafox1 01:55, 24 October 2007 (UTC)


 * Hi Gafox1. Could you reproduce the full Stearns reference please?  It not one I'm familiar with and I wouldn't mind a quick look at it (by way of a refresher).  Regarding the "death" of r/K, well, that may be somewhat exaggerated.  A quick trawl of the literature reveals that there are researchers out there using the concept (e.g. Caroli, L. et al., 2000, Zoo. Sci. 17, 209-216; Okada, H. et al., 2005, Nematology 7, 843-849; Hamer, A.J. et al., 2007, Aust. J. Zoo. 55, 79-88), but the relative paucity of hits suggests that you're generally correct (or that I can't search for toffee).  It could just be that most researchers have found it too constricting a concept for the species they work on, and so have moved onto more fertile theoretical territory.  However, as per the cites above, there are still workers out there who find it a useful concept.  I should add that my own experience is in marine ecology, where most theoretical ecology concepts (including r- and K-strategist) don't get much of a look in!  That said, I found quite a few aquatic hits in my trawl - suggesting that aquatic ecology is possibly catching up to terrestrial ecology from the 1970s; perhaps we'll ditch the concept in 10 years time!  ;-)  --Plumbago 07:52, 24 October 2007 (UTC)

Here's the Stearns cite: Stearns, S. C. Evolution of life-history traits - critique of theory and a review of data. Ann. Rev. Ecol. Syst. 8: 145-171. This paper was very influential for 10 or 15 yrs -- for some time it was *the* standard reference for much about life history theory. That's not to say that it was the definitive work -- just that it was widely read and cited.

In addition to Stearns' criticism, it's worth asking two things about r/K theory. First, the theory was derived from logistic growth models, but a moment's thought will tell you that the derivative of the logistic equation with respect to both r and K is positive. In other words, there's no necessary trade-off in that model -- one must add other assumptions, usually ad hoc. Second, is r/K theory actually testable? If you go to look inside a population and study its evolution, how could you test it?

I've heard it said before by marine ecologists that marine ecology tends to be light on theory. Maybe it's true -- I don't get wet in my work, so can't say. All I'll say is that if you look at leading journals on ideas in evolutionary biology -- say, Evolution and Am. Nat., or others if you like -- you'll find that r/K theory hasn't inspired substantial work in a long time. It seems to have been resurrected lately because, well, it's a simple explanation for something that's complicated -- so it's made a reappearance in places like textbooks. My own view is that this is a bad thing: the theory doesn't work logically and it led to a real mess empirically; there are good reasons to discuss it as part of the history of science, but not as a currently viable theory.

By the way, you might also look at Derek Roff's book on life histories and their evolution. I don't recall what he says about r/K theory, but that's just the point -- it plays little role.

Cheers, Gordon Gafox1 00:28, 25 October 2007 (UTC)

Hey Gordon,

As a professor who teaches about r/K selection in my courses, I was a little surprised to find that the first line of this entry states that R/K theory has been largely discredited. As I work primarily on empirical population genetics, I thought that perhaps I had simply not kept up with the literature in this arena. However, after doing a little digging, I'm not sure the evidence supports you.

I did go and read Stearns' article, which it is worth pointing out is itself rather old -1977. The current editions of both Futuyma's "Evolution" (the standard textbook for Evolutionary Biology) and Ricklefs' "Ecology" (the premier textbook in population ecology) both discuss r/K selection in some detail, and both of these textbooks were revised within the last ten years.

I noted in your talk post (above) your disdain for textbooks as sources (perhaps a reasonable position), so I did some searches on Web of Science. I find that there have been 43 paper published in the last 20 years that have the term "r/K selection" in the abstract or the keywords and that are in journals relevant to ecology and evolution. You mention Evolution and American Naturalist as your gold standard for journals in evolutionary biology (having recently published in both, I would agree that these are the best journals out there! ;)). Here are two articles about r/K selection, one from each of these journals, one of which is quite recent:

Title: Shift in colonial reproductive strategy associated with a tropical-temperate gradient in Rhytidoponera ants Author(s): Molet M, Van Baalen M, Peeters C. Source: AMERICAN NATURALIST  Volume: 172   Issue: 1   Pages: 75-87   Published: JUL 2008

Title: Laboratory evolution of life-history traits in the bean weevil (Acanthoscelides obtectus): The effects of density-dependent and age-specific selection Author(s): Tucic N, Stojkovic O, Gliksman I, et al. Source: EVOLUTION  Volume: 51   Issue: 6   Pages: 1896-1909   Published: DEC 1997

Lastly, I'm not sure that I agree that simply because there is no clear trade-off between reproduction and competition visible in the logistic equation itself should tell us that there is not a biological reality to r and k strategies. It merely tells us that if r/K trade-offs exist, they are not captured in a vastly oversimplified equation. The logistic equation does not account for the effects of age structure either... would you therefore contend that Lewis Leslie Matrix Models should be abandoned? More seriously, we see that there are good physiological reasons to expect that there is a trade-off between producing fewer, more vigorous offspring, and producing more, lower quality offspring. This expectations is supported by numerous empirical studies.

I'm not saying you're wrong, and I hope this post doesn't seem like a flame... I honestly am not a good student of life history evolution, so I don't pretend to be an expert here. All that I am saying is that to me - as a quasi independent observer - it doesn't look like this theory has been debunked.

Lastly, to strike a perhaps more conciliatory tone, although I have not read Derek Roff's book, which you suggest as further reading on this issue, Roff is quoted in the current edition of Ricklefs. The full passage reads as follows:

"To summarize, the concept of r- and K- selection has been useful in helping to formalize the definition of fitness in density-regulated populations, but attempts to transfer the concept to actual populations without regard to the realities of the complexities in life history have probably been detrimental rather than helpful"

Although clearly not a ringing endorsement of r/K selection, neither does Roff seem to indicate that the whole idea has been abandoned.

Your thoughts?

Moneilema. —Preceding unsigned comment added by Moneilema (talk • contribs) 16:35, 15 April 2009 (UTC)

April 15, 2008

Ok, So I went and looked at Roff's book. In fact what he says is that r/K theory is applicable only when considering density dependency within species, and calls for studies that specifically quantify selection acting on reproductive strategies when populations are either near their carrying capacity, or below K/2. Roff also identifies a recent (at the time that he was writing) study which he considers to be an excellent example of how r/K selection should be explored: Density-dependent natural selection in Drosophila: evolution of pupation height. LD Mueller, VF Sweet - Evolution, 1986.--Moneilema (talk) 17:24, 18 April 2009 (UTC)

It is true that Roff only spends about a page talking about r/K theory, but that seems to be primarily because the models he explores do not consider density dependency.

Given that, in fact there seems to be a rich literature on r/K selection in the last ten years (see previous post, including papers from Evolution and American Naturalist), particularly in the areas of genome evolution, and given that Stearns' article is more than 30 years old, I do not think it is appropriate to label r/K selection as discredited. On this basis, I have removed the label on the first line indicating that r/K selection has been discredited. I have retained the "status of the theory" section at the end of the article.

Feel free to undo my edit if it seems I am overreaching.

Moneilema.

--Moneilema (talk) 17:24, 18 April 2009 (UTC)

Opportunistic / Equilibrium Populations
I was updating my class notes on the topic. Several references incorporate the terms opportunistic population and equilibrium populations into the general descriptions. I didn't see any reference to those terms here. It shows up in Campbell/Reese as well with those descriptors. Is anyone still invested in this article that wishes to work it in? --JimmyButler (talk) 00:23, 7 April 2008 (UTC) Here is an excellent reference if it needs a citation.



Two basic types of life strategies have been distinguished in eukaryotes. Populations that are subject to disturbances and thus grow in regular or erratic bursts are called opportunistic populations, whereas those which exist at more stable densities are termed equilibrium populations. Opportunistic populations typically grow fast, whereas equilibrium populations have a high competitive ability.http://en.wikipedia.org/skins-1.5/common/images/button_sig.png Your signature with timestamp


 * Hi JimmyButler. I've put a sentence in to mention these terms.  I've used the reference you cite above (which mentions r- and K-selection shortly after the end of the quotation above).  Is this OK?  Cheers, --Plumbago (talk) 09:43, 7 April 2008 (UTC)


 * Works for me. Thank you--JimmyButler (talk) 00:35, 11 April 2008 (UTC)

r/K and one-child policy
User:Ksyrie is going across articles on multiple Wikipedias adding seealso links between this article and one-child policy (see, for example, this). As far as I can tell, the connection is tangential at best, and original research. I don't see any reason for inclusion of this seealso. r ʨ anaɢ talk/contribs 04:29, 8 May 2009 (UTC)


 * It's gone. Beyond being about number of offspring, it has no connection to this topic at all.  Thanks for flagging it up.  --P LUMBAGO  13:32, 8 May 2009 (UTC)

Rushton again
Rushton's definition of "race" does not agree with the accepted biological definition "race = subspecies". See any university-level biology textbook that discusses the question. By the standards of Dd2, any flat-earther could complain about not being given due attention on WP. WP:VERIFY does not change a shred about the fact that in the sciences we have something called falsification, and that WP:UNDUE stands above all policies designed (like WP:VERIFY) to avoid disputes of opinion: Earth is not flat, and while anyone can redefine "gravity" to "prove" a flat Earth, pseudoscience is still pseudoscience, and similarly Rushton's "races" are a complete and utter fiction.

Speaking from my professional training in ecology, the life history differences between any two human populations are not large enough to differentiate on the r/K spectrum, because Homo sapiens is a K strategist to the extreme, the same league as whales and elephants. r vs K strategists, we're talking about the life-history differences between elephants and mice here. r strategists typically having one batch of dozens or even thousands of offspring and not living to reproduce a second time, and such things. r/K selection, furthermore, is something that changes within geological time, not in the few puny millennia since the start of civilization. Rushton has as much understanding of biology as Robert Mugabe has about economy; or perhaps less considering Zimbabwe's economy is a farce, but at least exists.

Sources:
 * Begon, M.; Townsend, C.R. & Harper, J.L. (2006): Ecology: From individuals to ecosystems (4th ed.). Blackwell. ISBN 1405111178 (Chapter 4) <- a good allround source for the entire article
 * Cavalli-Sforza, Luigi (2000): Genes, Peoples, and Languages. North Point Press. ISBN 0865475296 (all of it)

(FWIW, the Sentinelese qualify as a distinct human race more than almost anyone else. And for a fictrional example where that what Rushton proposes does hold true, see the differences between Middle-earth Common Men and Elves - though biologically, Elrond and Elros nonwithstanding, they are "species" not "races", and of course ) Dysmorodrepanis (talk) 13:48, 11 August 2009 (UTC)


 * Hi Dysmorodrepanis. Do you have a specific change that you'd like to make?  The article is not endorsing Rushton's ideas but merely reporting them, together with references to sources that dispute them.  Regarding the current text, I don't think we need to go into the detail of Rushton's ideas, since this is covered elsewhere.  And I would prefer that his ideas are labelled as scientific racism (as they previously were until a recent edit).  However, I don't think that the current text is promoting his ideas, and I think that it covers the criticism of them adequately.  Do you disagree?  --P LUMBAGO  15:33, 11 August 2009 (UTC)


 * It is my personal observation that humans alter their child bearing strategy depending on their individual life circumstances. Pioneer families had large families, and spent little on their education. During the Depression, few couples had large families, instead they spent large sums on the education on the one or two children they did have. This trend continues today. Before the advent of modern medicine, couples generated multiple infants being aware that few would live to have children of their own. It should be obvious that humans are unique in choosing their reproduction strategy based on their individual assessement of circumstances. Don (talk) 20:18, 29 August 2009 (UTC)


 * Hi Don. The problem here is not about what we personally think about the r/K spectrum's relationship to humans (for the record, I completely disagree with Rushton), but whether Rushton's scientifically racist views should be represented in the article.  While I think that it's a flimsy one, I can see a case for having a brief mention of Rushton's work in this article.  But I'm pretty ambivalent about this and am happy to discuss whether it should remain.  Cheers, --P LUMBAGO  16:39, 3 September 2009 (UTC)


 * I notice that an anonymous user has just removed the reference to Rushton's theory from this article without first discussing it here. Whoever removed this information, please don't blank parts of articles at Wikipedia without first proposing these edits on the relevant discussion pages, and obtaining consensus for doing so. --Captain Occam (talk) 07:54, 4 October 2009 (UTC)

trees as K?
Why are trees listed as an example K-selection? They are sometimes big, yes, but they invest less in their offspring than most reptiles, produce sometimes hundreds of thoudands of seeds per season (virtually none of which will survive to sexual maturity or even germinate) and distribute them over vast ranges. Seems to me they are classic r. —Preceding unsigned comment added by 220.233.36.78 (talk) 05:30, 8 November 2010 (UTC)


 * The article says that trees have K-selected traits. Which they do - they invest heavily in organism size, are strongly competitive and extremely long-lived.  The article goes on to give trees as an example of why r/K should be considered a spectrum rather than a simple binary split, and gives trees as an example that have both r- and K-selected traits.  Which part seems to be the problem?  --P LUMBAGO  08:33, 8 November 2010 (UTC)

The physical characteristics of trees are irrelevant, plant life takes place on a different scale, and r/K are evolutionary strategies. Plumbago, are you the one who decided to use a book on minding children as the citation for declaring trees, the classic r, to be K?

This is probably my favourite wikipedia article, it's hilarious how badly you people have messed it up. Issue313 (talk) 16:07, 15 December 2013 (UTC)]

math and words
What's the relationship of k-strategists and r-strategists to the differential equation presented? N converges to K regardless of where you start or what r is. I can sort of see how high-r (some kind of "intrinsic growth rate) is high fecundity while high-K is offspring quality (efficient use of existing resources or something) but both kinds of species exhibit stable dynamics so what's the discussion about "unstable environments" have to do with this? At very least this is very unclear.Volunteer Marek (talk) 06:34, 5 April 2011 (UTC)


 * I think that you're reading a little too much into the equation. For starters, it's a highly simplified summary of population dynamics that omits almost all biological detail.  In fact, all it has is a population, N, a growth rate, r, and a carrying capacity at which population growth ceases, K.  There's nothing in there about trophic status (autotroph, heterotroph, saprotroph) or relationships with other organisms (prey, grazer, carnivore).  As such, to represent this the rather crude equation would take on high r and low K for an r-selected species, and the reverse for a K-selected species.  All that said, if you find it difficult to understand, then it's very likely that other readers will too, so we need to work on that.  How's about rewording the section around the equation to something like ...
 * "In r/K selection theory, selective pressures are hypothesised to drive evolution in one of two generalized directions: r- or K-selection. These terms, r and K, are derived from standard ecological algebra, as illustrated in the highly simplified Verhulst equation of population dynamics: where r is the growth rate of the population (N), and K is the carrying capacity of its local environmental setting. As the name implies, r-selected species are those that place an emphasis on a high growth rate (high r, low K), and typically exploit less-crowded ecological niches and produce many offspring, each of which has a relatively low probability of surviving to adulthood.  By contrast, K-selected species display traits associated with living at densities close to carrying capacity (low r, high K), and typically are strong competitors in such crowded niches that invest more heavily in fewer offspring, each of which has a relatively high probability of surviving to adulthood.  In the scientific literature, r-selected species are occasionally referred to as 'opportunistic', while K-selected species are described as 'equilibrium'."
 * Does this work any better for you? Cheers, --P LUMBAGO  08:16, 5 April 2011 (UTC)


 * No, not really. Basically I think I'm having two issues with this:
 * One - what's the link between the equation and the word description? I fully realize and appreciate the need for parsimony and simplicity but there hardly seems to be any connection. In particular the phrasing These terms, r and K, are derived from standard ecological algebra, as illustrated in the highly simplified Verhulst equation of population dynamics is at best inaccurate. Neither r nor K are derived from anything, they're constants. N is derived. Also selective pressures are hypothesised to drive evolution in one of two generalized directions: r- or K-selection - that's not in the equation at all. It might be in some other equations but not in this one. Hence it is inaccurate to say that the equation "illustrates" these selective pressures.
 * Two - as I stated above, the discussion of "unstable environments", where does that come from? The equation describes a stable dynamical system. Both hi-r and hi-K (or lo-r and lo-K or any combination of {r,K}) exhibit stable dynamics. So again, this "instability" might be in some other equation(s), but it's not here.Volunteer Marek (talk) 08:27, 5 April 2011 (UTC)
 * If you could maybe point me to a paper/textbook that lies out the theory formally maybe I can figure this out. I understand the logic of the words. I understand the math. I just don't see how the two connect except for that somebody used the letters "r" and "K" in both of them.Volunteer Marek (talk) 08:31, 5 April 2011 (UTC)


 * (Edit conflict) OK.  On your first point, how's about replacing "derived from" with "drawn from"?  The intention was not to imply "derived" in a strong, mathematical sense, although given that an equation is involved, I can see why this may be confusing.
 * On your second point, the Verhulst equation is not meant to describe every known system, or include all factors known to influence population dynamics. As noted in the article, it is a highly simplified version of reality that only aims to be a first order description.  One could tweak it to include some element that represents a changeable environment, but that's going too far for here IMHO.  It is simply the source of the terminology that r/K selection theory uses.  As it happens, there are many ecological models that do represent aspects such as environmental changeability, and these implicitly (or explicitly) represent r and K.  But they weren't the source of the terminology, and are far too complicated (unnecessarily so) to merit inclusion here.
 * Regarding a source, you're probably best trying to track down the Pianka reference (number 1 in the reference section). There's also a short commentary on it by Pianka himself available here that might be useful to you.  There's also the critical reappraisal of r/K selection theory by Stearns that might help.  Failing all that, and if you have access to the scientific literature, just poke around — there's quite a body on r/K.
 * I hope this helps. Cheers, --P LUMBAGO  08:57, 5 April 2011 (UTC)


 * The Stearns paper helps a little bit. Pianka, not really. I'm basically looking for a formal presentation of the model.Volunteer Marek (talk) 20:51, 5 April 2011 (UTC)

Ah, ok, looked some stuff up. So r can be negative - in which case the only stable level of population is 0, while there is also an unstable equilibrium at K. Just putting that in would help clarify things. Of course r<0 has some very unrealistic implications if N(0)>K.

Question - is there some maximization of fitness going on here which determines {r,K} - the wording of the text sort of implies it?Volunteer Marek (talk) 08:46, 5 April 2011 (UTC)

Answering myself So r can be negative - in which case the only stable level of population is 0, while there is also an unstable equilibrium at K. - but even this confuses cause and effect. r<0 CAUSES instability rather than vice versa. It sounds like what it's trying to say is that in environments with lots (or is it "large"?) of stochastic shocks (to what?) a higher r/lower K is better (for what?) but in environments with few (or is it "small"?) stochastic shocks lower r/higher K is better (again, for what?). So there's some confusion going on between the idea of mathematical stability of a dynamic system and frequency (or magnitude?) of shocks.Volunteer Marek (talk) 08:54, 5 April 2011 (UTC)


 * This is probably more appropriate for the article on the Verhulst equation itself (there's quite a bit of material there already). The equation is really the source of terminology (and broad concepts) rather than a rigorous underpinning of what passes for r/K selection theory.  Particularly so on the subject of stability, since real ecosystems, and even ecosystem models, are considerably more complex.
 * Regarding negative values of r, it's surely biologically unrealistic to describe that as a growth rate? As soon as a (constant) r has a value that is <= 0, its relationship with population dynamics is questionable (which isn't to say that population growth rate can't be zero, just that other factors come into play there).
 * However, I would still agree that something more quantitative about the role of disturbance in stability probably wouldn't hurt here, but I don't have the time to do work on anything like that at moment (and it's not exactly something I'm terribly au fait with anyway). Cheers, --P LUMBAGO  11:35, 5 April 2011 (UTC)


 * Ok the statement that the equation is the source of the terminology makes a lot more sense than saying that the equation describes the theory. The theory itself appears to be about what determines r and K, rather than the actual dynamics of how the populations evolve (which is what the equation is about) once these are given - though I'm completely lost as to how exactly r and K are determined, what is the actual variable that is being affected through which r and K are realized, and what the trade off involved between r and K is. Like for example:
 * r-selection predominates as the ability to reproduce quickly is crucial. There is little advantage in adaptations that permit successful competition with other organisms, because the environment is likely to change again. - why? What is this based on? A maximization (presumably of fitness) problem? If so what are the parameters here? Empirical evidence? Also, it seems like fitness maximization doesn't really care (much) about variance of shocks, just expected value. As a first pass if you're adopted to the average state of the environment, then probabilistically you'll do just as good (especially over long time periods) regardless of whether there's lots of "instability" or not.
 * This also sort of bugs me: "r is the growth rate", with a link to population to the population growth rate. The population growth rate is, by definition, (dN/dt)(1/N). Hence r cannot be the growth rate unless N=0 or K=infinity. I think this kind of terminology might be idiosyncratic to ecology so I'm probably being over sensitive and pedantic here.
 * Anyway, thank you for your response - I hope I haven't been too negative, just trying to understand the theory (partly in order to understand the article, partly for personal benefit) and best way to do that a lot of times is to ask lots of questions.Volunteer Marek (talk) 20:51, 5 April 2011 (UTC)


 * To be fair, the article does introduce the Verhulst equation because of its use of "standard ecological algebra" rather than its direct relevance to r/K selection. The wording could be tightened (as per my suggestion above?) to make this clearer though.  In fact, I'll do that now - I think this at least addresses some of your concerns.
 * Regarding how they are determined, r could be measured in a laboratory by simple population growth experiments (e.g. put organism in a flask, time how long it takes for its population to double given no growth impediments). In ecological models, r is usually included as a parameter - sometimes labelled as maximum growth rate (i.e. maximum possible growth rate), or as maximum uptake rate where a modelled "population" grows through uptake from a pool of some resource.  K is a more difficult concept to measure since it is not necessarily intrinsic to a particular organism.  For instance, the value of K is liable to vary spatially with the abundance of resources and/or predators.  That said, it's still the case that K can be partly determined by an organism itself though (e.g. in the case of photoautotrophs, high population density can lead to self-shading, which imposes something of a carrying capacity).  In ecological models, K, such as it is, is often not specified directly at all, and instead is more an emergent property driven by factors such as nutrient availability, predator abundance or disease mortality.
 * However, having said that, I don't think that this sort of information is necessary in this article since r/K selection theory is really using these terms as shorthand for broad ecological concepts rather than hard and fast quantitative assessments. I think, in fact, that this vagueness is one of the aspects that Stearns rightly questions in his reappraisal.  But regardless of this viewpoint, r/K selection theory is used to the present day in the literature, hence the subsequent comment on it by Stearns.
 * Of course, I say all this as someone who's never used r/K selection theory in my work, though I can still see how it could be a useful way of interpreting ecological facts. Anyway, what I'm saying is, don't take my views as gospel, second opinions are encouraged.  I hope this helps.  Cheers, --P LUMBAGO  08:15, 6 April 2011 (UTC)
 * Ok, thank you so much - your explanations did help me a lot. I changed the labeling on r to "maximum growth rate", otherwise it will just bug me forever. As far as I understand your explanation r and K are determined more or less empirically, with a bit of hand waving, and this is the part criticized by Stearns (and possibly others). So there is no explicit model - like an optimization problem or some kind of a evolutionary game theory model - which endogenizes these two parameters/variables. Again, thanks!Volunteer Marek (talk) 17:36, 6 April 2011 (UTC)


 * Glad that was of use. I think the article's been changed slightly for the better too, so this has been useful.  Regarding the theory, yes, it has been attacked by others as well as Stearns, but it is (apparently) considered useful enough for people to still use it (cf. the Stearns quotation).  Cheers, --P LUMBAGO  12:47, 7 April 2011 (UTC)

POV lead
Two 1992 books are hardly evidence for current status. Also, that authors may criticize a theory does not prove conclusively that the theory is falsified.Miradre (talk) 18:28, 13 April 2011 (UTC)
 * No the fact that two prominent evolutionary biologists say specifically it has been falsified and that it has gone out of use, and show evidence that the number of people using it was declining rapidly in the period from 1989-1992 is pretty good evidence. You would have to present very good evidence to the contrary to contradict this. I have checked two recent evolutionary ecology textbooks that use life history theory and none of them mention the model. ·Maunus· ƛ · 19:03, 13 April 2011 (UTC)
 * Here are some recent books mentioning the theory: Ecology from ecosystem to biosphere, C. Lévêque, 2003. Textbook of Environmental Microbiology, Mohapatra, 2008. Biology of fishes, Q. Bone, Richard H. Moore, 2008. Ecology Basics, Salem Press, 2003. Ant ecology, Lori Lach, Catherine L. Parr, Kirsti L. Abbott, 2010. Insect ecology: an ecosystem approach, Timothy Duane Schowalter, 2006. So the claim that is does not appear in biology books is simply false.Miradre (talk) 19:04, 13 April 2011 (UTC)
 * I didn't not claim that. I said that it wasn't mentioned in ther two textbooks I checked, which it doesn't. Now what does those books say? And furthermore even if they do mention the theory favorably that does not provide a counter claim to Graves and Stearns unless they mention them specifically. Just stating that x number of books still mention the theory would be SYNTH unless they explicitly contradict Graves' and stearns conclusions. ·Maunus· ƛ · 19:21, 13 April 2011 (UTC)

While the general use and application of the theory in biology is a legitimate topic, the fact that some racists have hijacked the theory to push their agenda is neither here nor there. Racist organizations have usurped all kinds of bits and pieces from all kinds of fields in order to "dress up" their ideas in pseudo-scientific garb. There's no reason why Wikipedia needs to serve as a forum for this kind of disinformation. At most a short statement that some racists "researchers" have tried to exploit the theory, and misapplied and misunderstood it in the process, in order to further their racist ideology would be sufficient. So the Rushton's section goes.Volunteer Marek (talk) 21:22, 13 April 2011 (UTC) As for Stearns and Graves empirical evidence falsifying the theory has been given as well as evidence that it was gradually abandoned. I have searched databases myself and have barely found any reference to it. EgalitarianJay (talk) 03:01, 14 April 2011 (UTC)
 * We probably don't need the Rushton section in there because when I think about it his view is fringe. The criticisms of his application of r/K selection are on his Wikipedia page and the page for his book so Rushton doesn't even need to be mentioned here.
 * See the textbook above mentoning it.Miradre (talk) 05:20, 14 April 2011 (UTC)


 * "The theory of r- and K-selection was one of the first predictive models for life-history evolution. It helped to galvanize the empirical field of comparative life-history and dominated thinking on the subject from the late 1960s through the 1970s. Large quantities of field data were collected that claimed to test predictions of the theory. By the early 1980s, sentiment about the theory had changed so completely that a proposal to test it or the use of it to interpret empirical results would likely be viewed as archaic and naïve. The theory was displaced by demographic models that concentrated on mortality patterns as the cause of life-history evolution. Although demographic models are known for their density-independent approach and focus on extrinsic mortality, these models can incorporate many ecological features captured by r- and K-selection, such as density-dependent population regulation, resource availability, and environmental fluctuations. We highlight the incorporation of these factors in recent theory, then show how they are manifest in our research on life-history evolution in Trinidadian guppies (Poecilia reticulata). Explanations of the repeatable suites of life-history differences across populations of guppies originate from demographic models of predator-driven age-specific mortality. Recently, careful examination of guppy demography and habitat has revealed that density-dependent regulation and resource availability may have influenced the evolution of guppy life histories. In the field, these factors covary with predation risk; however, they can be uncoupled experimentally, providing insight into how they may have synergistically driven guppy life-history evolution. Although life-history theory has shifted away from a focus on r- and K-selection, the themes of density-dependent regulation, resource availability, and environmental fluctuations are integral to current demographic theory and are potentially important in any natural system." (r- AND K-SELECTION REVISITED: THE ROLE OF POPULATION REGULATION IN LIFE-HISTORY EVOLUTION David Reznick, Michael J. Bryant, and Farrah Bashey 2002)·Maunus· ƛ · 12:10, 14 April 2011 (UTC)


 * Comparative Primate Ecology by P . C Lee (2001) p. 78 "R/K theory was widely used in early studies of life history .... The model has now been replaced... because a large number of studies have shown that the r/K model does not explain" ·Maunus· ƛ · 12:10, 14 April 2011 (UTC)


 * Directionality theory: an empirical study of an entropic principle in life‐history evolution. Martin Ziehe Lloyd Demetrius. Proc. R. Soc. B 7 June 2005 vol. 272 no. 1568 1185-1194 "In the 1970s, the model of r–K selection emerged as an influential response to this challenge (Pianka 1970, after MacArthur & Wilson 1967). Although this model provided some qualitative insight into the relationship between ecological constraints and life-history characteristics, its weakness as a predictive model is now recognized (Stearns 1992; Reznick et al. 2002). These shortcomings derive largely from the fact that the r–K selection model (in its analytic expression as distinct from its more qualitative claims) is essentially concerned with populations in which fertility and mortality variables are independent of age. Accordingly, the model is unable to explain in quantitative terms the correlation between ecological conditions, such as density-dependent constraints, and age-dependent life-history characteristics, such as age of sexual maturity, reproductive span and longevity. "·Maunus· ƛ · 12:25, 14 April 2011 (UTC)


 * The K-factor, covitality, and personality. from washington.eduAJ Figueredo, G Vásquez, BH Brumbach… Human Nature, 2007. Springer"When the empirical evidence failed to completely support the original r/K theory, however, other theorists suggested that the model was incomplete and that variation in predation needed to included in the model (Reznick, Bryant, and Bashey 2002). Once this parameter was incorporated, demographic theory became the predominant view for understanding mechanisms underlying life history strategies (Stearns 1992). This theory focuses on age-structured populations, specifically attending todifferential mortality rates across age groups (Charlesworth 1980). Current life history theories tend to incorporate features from both r/K and demographic theories. A universal feature of all these models [r/K and demographic models] is that environmental effects operate through age- or stage-specific effects. Thus, density-dependent regulation or stochastic effects interact with demographic selection, so that the predicted optimal life history is a function of both demographic selection and the way these additional environmental effects are manifested" (Reznick, Bryant, and Bashey 2002:1515)."·Maunus· ƛ · 12:29, 14 April 2011 (UTC)


 * The discounted reproductive number for epidemiology. TC Reluga, J Medlock… - Mathematical Biosciences and …, 2009 "The r{K selection theory was originally envisioned as a continuum between r selected species in resource-rich environments that evolve to maximize productivity and K selected species in resource-scarce environments that evolve to maximize efficiency. The nomenclature derives from the simple logistic-growth model [mathematical formula] where r represents the per-capita growth rate and K denotes the carrying capacity. In application, however, r{K selection has most often been treated as a polar dichotomy because there is no natural continuum between the carrying capacity K, measured in the same units as the population's size, and the growth rate r, measured in units of inverse time. Although it is a convenient caricature, r{K selection theory has been largely abandoned."·Maunus· ƛ · 12:35, 14 April 2011 (UTC)
 * Your own sources does not state that theory has been falsified. Only that it was incomplete. From your first: "Although demographic models are known for their density-independent approach and focus on extrinsic mortality, these models can incorporate many ecological features captured by r- and K-selection, such as density-dependent population regulation, resource availability, and environmental fluctuations." From the conclusions of your first paper: "This new life-history paradigm has matured into one that uses age-structured models as a framework to incorporate many of the themes important to the r–K paradigm." r/K theory lives on in a modified version.Miradre (talk) 13:03, 14 April 2011 (UTC)
 * Or from the Figueredo et al paper you quoted above: "Current LHT tends to incorporate features from both r-K and demographic theories. Integrating age-specific mortality parameters provided better predictions and mechanistic explanations for the relationship between the environment and life history strategy (Wilbur, Tinkle, and Collins, 1974). As a model of ecological causation, Pianka's (1970) version of r-K theory has thus been extensively elaborated and revised since the 1980s (Reznick, Bryant, and Bashey, 2002; Stearns,1992). Nevertheless, as an organizing principle for empirical description, the general patterning of life history traits has gained continued support (e.g., Rushton, 2004)."Miradre (talk) 13:02, 14 April 2011 (UTC)
 * So does Flat earth theory. You are grabbing at straws.·Maunus· ƛ · 13:06, 14 April 2011 (UTC)
 * The flat earth theory is not incorporated in later theories. rK-theory is as your own sources state. Even citing Rushton! Miradre (talk) 13:10, 14 April 2011 (UTC)

Etymology?
Do we know where the name "r/K" comes from? I've seen it speculated (but would be loath to add to the article without substantiation) that it's a reference to the different breeding strategies of the rat and Kangaroo... DS (talk) 12:19, 13 August 2011 (UTC)


 * It's based on the logistic growth equation r is the intrinsic growth rate and K is the carrying capacity. Nope, no sources handy at the moment. Guettarda (talk) 20:59, 13 August 2011 (UTC)


 * Do you have one by now by any chance?:) Best wishes,--Vergänglichkeit (talk) 21:23, 29 July 2023 (UTC)

When presenting mathematical formulae please define ALL the terms used.
I almost understand it, but "d" and "t" are not defined. There are no links to other pages that might explain. The purpose of Wikipedia is to teach. I want to learn. Formulae that are not fully defined and not linked are like a brick wall impeding my progress. Just give me some links to follow people. Thanks. — Preceding unsigned comment added by 70.41.216.250 (talk) 19:30, 12 March 2012 (UTC)

More Rushton Flip flopping
I think it is appropriate to include a note about Rushton, with appropriate links to pro and anti Rushton sites. Rushton's analysis is one of the things that has made R/K selection theory notable (see all previous posts and the warnings at the top of this page!!). You can't just remove it.. This Wikipedia article is where people will come when they hear about the theory, so I think a paragraph or two can be justified. I don't think it's UNDUE. It would be undue if nobody had heard of Rushton. Like it or not many have.

Let's look a similar things such as global warming the holocaust criticism of Islam and evolution, to see how these things are handled. They are not handled by removing all references to the counter arguments altogether, or by peppering most of the account with the "minority theory" but are dealt with by a paragraph in the main article, and a link to another article. I think this is what should be done here. Mike Young (talk) 06:25, 13 April 2012 (UTC)


 * Rushton made r/K selection notable? How so? You have a source to support that? As for edit-warring, you're the one who has reverted two different editor without bothering to explain your position. If you want a "similar thing", look at how Raëlian intelligent design is covered in the intelligent design article - it's in the "See also". Which is what I did here. Though frankly I think the Raëlians are more notable than Rushton, while r/K selection is obviously more notable than ID. Guettarda (talk) 11:28, 13 April 2012 (UTC)


 * I mean - look at the sources in that section: we have one primary source, and three sources that say it doesn't belong. Guettarda (talk) 11:33, 13 April 2012 (UTC)


 * In addition, if you look at the history here, you have hardcore "race and intelligence" people pushing this into the article. Which explains a lot of the problems with perception - it's a big deal in people interested in Rushton's work. The problem is that the relationship is clearly asymmetrical. Rushton's stuff is minor, fringe or near fringe. Population ecology and life history evolution, on the other hand, is mainstream stuff. And that's the domain of r/K selection. Rushton (mis)appropriated the idea, but that simply makes this stuff important to his work, it doesn't make his stuff important to this article. Another way to look at this - imagine if we added a section of every hypothesis is population ecology that was built on r/K selection. We'd have a ridiculously long article. And yet, almost every one of those would be more applicable to the mainstream use of r/K theory than Rushton's stuff. Guettarda (talk) 12:40, 13 April 2012 (UTC)
 * I agree. Rushton´s work is fringe and needs only the briefest of mentions here. User:Maunus ·ʍaunus·snunɐw· 00:34, 13 November 2013 (UTC)

Rushton's work on r/K selection was heavily relied upon by Herstein and Murray in The Bell Curve. Dmcw127 (talk) 23:10, 12 November 2013 (UTC)
 * Correct. That should be treated in the article on that topic.User:Maunus ·ʍaunus·snunɐw· 00:34, 13 November 2013 (UTC)

r-selected species: high r, low K...?

 * "r-selected species are those that place an emphasis on a high growth rate, and typically exploit less-crowded ecological niches and produce many offspring, each of which has a relatively low probability of surviving to adulthood (i.e. high r, low K)"

--Sgmanohar (talk) 17:27, 3 May 2012 (UTC)
 * Well I don't understand how "less-crowded" means LOW K. Surely it is high K? can you explain this in the article, thanks!
 * Yes, this needs to be explained by someone who knows what (s)he is talking about. My uninformed take on it is that r-selected species simply don't spend energy on increasing their K value, hence rendering it low compared to what it could possibly be considering only external factors. This doesn't mean that their K value will be low compared to that of other species. Of course a typical r-selected species (say, some kind of shrimp) will have much higher K values than a typical K-selected species (say, polar bear). 85.226.207.245 (talk) 10:55, 22 September 2012 (UTC)

Nidicolous
Isn't being nidicolous the same as being K selected? FunkMonk (talk) 05:03, 10 July 2012 (UTC)

r and k
What do r and k actually stand for? I get that r might mean reproduction or am i wrong? Difficultly north (talk) - '' Simply south alt. '' 13:12, 9 May 2013 (UTC)


 * It already says in the article quite clearly. Have another look.  --P LUMBAGO  06:26, 11 May 2013 (UTC)


 * Yes, but sadly it's not sourced, also not in Carrying capacity. Do you know any source, P LUMBAGO ? Best wishes,--Vergänglichkeit (talk) 21:23, 29 July 2023 (UTC)
 * @Vergänglichkeit - I think the terms might originate in MacArthur and Wilson's 1967 work, The Theory of Island Biogeography. I don't have it to hand, but I'll see if I can dig it up. Cheers, --P LUMBAGO 20:32, 1 August 2023 (UTC)

Still used in college textbooks
This edit removed sourced content with an edit summary stating that it's "still the dominant theory in college biology textbooks". Be that as it may, textbooks are lagging indicators, and general biology textbooks are especially bad. A sourced qualification might be helpful, but simple deletion isn't a good solution. Guettarda (talk) 16:15, 9 August 2013 (UTC)

Intelligence citations bibliography for updating this and other articles
You may find it helpful while reading or editing articles to look at a bibliography of Intelligence Citations, posted for the use of all Wikipedians who have occasion to edit articles on human intelligence and related issues. I happen to have circulating access to a huge academic research library at a university with an active research program in these issues (and to another library that is one of the ten largest public library systems in the United States) and have been researching these issues since 1989. You are welcome to use these citations for your own research. You can help other Wikipedians by suggesting new sources through comments on that page. It will be extremely helpful for articles on human intelligence to edit them according to the Wikipedia standards for reliable sources for medicine-related articles, as it is important to get these issues as well verified as possible. -- WeijiBaikeBianji (talk, how I edit) 16:00, 28 August 2013 (UTC)

Equation graph
I'd like to request that someone produce a 3-dimensional graph to add to the "Overview" section, showing the relationship between $dN/dt$ (z-axis, or height of the graph) and the values of r (x-axis) and N (y-axis). z increases as r increases, and also increases as N decreases, producing a curved (linear in the x direction but hyperbolically curved in the y direction) surface. Any takers? — Loadmaster (talk) 02:24, 21 September 2014 (UTC)


 * I'm not sure that this is necessary - the equation is only reproduced here to illustrate where the terminology (r, K) comes from. What you're describing sounds like it might be appropriate to the page describing the logistic function, but it would be tangential here.  Cheers, --P LUMBAGO  10:22, 22 September 2014 (UTC)

Mouse picture is a rat
Hello, I'm new to WP editing, so I'm just going to post this and hope someone else takes it up. The "mouse" picture on this page is most definitely a picture of a rat. It's still a perfectly good example, just mislabeled in the caption and in the source file name. 89.204.139.90 (talk) 04:39, 30 October 2014 (UTC)


 * @89.204.139.90 It's definitely a mouse. I'm a breeder of both species and that's not a rat. The head is much smaller than in Rattus norwegicus, the tail is too thin for a rat, the body and head proportions are that of a mouse. The ears are much bigger in proportion to the head than in rats and the head itself is way too small for a rat. Rats have much bulkier skull especially in the snout area. 87.214.32.176 (talk) 18:58, 17 August 2022 (UTC)
 * @87.214.32.176 Addition because I can't edit: Also, the tail of the animal in the picture is smooth. Rattus norwegicus has a visibly scaly tail in females as well as in males. The ear spacing is much smaller, in rats the ears are visibly further apart not only in the dumbo phenotype but also in the standard top ear. The distance from the eyes to the tip of the nose is almost twice as long in rats, in proportion to the rest of the head. I could add a photo of an actual rat mother with newborn pups for comparison but I'm not sure if it's necessary for the article itself. 87.214.32.176 (talk) 19:14, 17 August 2022 (UTC)

Seems about right.. ! That mouse is a rat.ParanoidLemmings (talk) 23:53, 29 December 2014 (UTC)

Has r/K-Selection really been replaced with life history theory?
I have made a translation of this article on the danish wikipedia, and became somewhat unsure about that point. Sure r/K-selection is not used widely anymore on its own, but Life history theory incorporate most of the model. Saying the model have been replaced might misrepresent that point.ParanoidLemmings (talk) 10:18, 26 February 2015 (UTC)
 * Life History theory and R/k selection theory are different, even if the aspect of r and K selective reproduction strategies are also a part of Life istory - it does not attempt to deduce a host of secondary characters from that aspect alone which was what made R/k theory fail.User:Maunus ·ʍaunus·snunɐw· 15:33, 26 February 2015 (UTC)

Furthermore, what about rK-selection in human races?ParanoidLemmings (talk) 10:36, 26 February 2015 (UTC)
 * That was pseudoscientific nonsense from the beginning, and has never been taken seriously.User:Maunus ·ʍaunus·snunɐw· 15:33, 26 February 2015 (UTC)
 * In humans? That's just a misrepresentation by Rushton's folks. Guettarda (talk) 13:07, 26 February 2015 (UTC)

Okay, wont add anything about it in the danish wikipedia then. thx.ParanoidLemmings (talk) 17:54, 26 February 2015 (UTC)


 * Definitely don't add anything re: rK in humans - that's an attempt (IMHO) to cloak racism in scientific-sounding language. Regarding your original question, it seems to me that certain concepts from rK have been assimilated into modern (and much broader) life history theory.  rK was a first order (cartoon) attempt to determine patterns in life history across organisms, so while it's a good fit for some species, it misses out key features of others.  Life history theory is a more systematic treatment of how organisms go about their lives, one that doesn't try to shoe-horn all organisms into two not-entirely-representative modes of life.  --P LUMBAGO  09:45, 27 February 2015 (UTC)

r/K theory is a forerunner of life history theory. Life history theory is broader. Now r/K theory can be considered a subset of life history theory. Some prefer to use the terms fast versus slow life history instead of r versus K reproductive strategy, but it is basically the same. The r/K theory is mainly used for describing differences between species, and rarely between individuals. The theory of human r/K differences should probably have a separate wiki page as it has developed into a separate research tradition dealing with individual differences in behavior. Agnerf (talk) 07:19, 9 April 2022 (UTC)

"In stable or predictable environments, K-selection predominates"
I get that it's intellectually pleasant to argue that claim in opposition with the previous paragraph, but can it be backed up, if not just false? [I'm really no expert, but I get that K-selection doesn't work well in unstable environments. But isn't saying they predominate in stable environments pushing it?] — Preceding unsigned comment added by Seub (talk • contribs) 08:45, 15 March 2015 (UTC)

Well can you give an example of K-species that lives in an unstable environment?ParanoidLemmings (talk) 08:55, 30 March 2015 (UTC)

Orchids as K?
Currently we have "A typical K reproducer is the orchid, or members of the Orchis genus.[citation needed]" I was tempted to just remove it, because it makes no sense to me. Orchids have many small seeds, that have almost no provisioning. That's why they're such a pain to propagate from seed- they need their fungal buddies.

In plants, K selection usually means fewer, larger seeds, with more provisioning. From Orchidaceae "The seeds are generally almost microscopic and very numerous, in some species over a million per capsule. After ripening, they blow off like dust particles or spores. They lack endosperm and must enter symbiotic relationships with various mycorrhizal basidiomyceteous fungi that provide them the necessary nutrients to germinate, so all orchid species are mycoheterotrophic during germination and reliant upon fungi to complete their lifecycles."

So, unless someone can give me a good citation for orchids as k-selected, I'm going to remove that soon, and put in a more canonical example (probably animal, because people can easily tell the difference between a million fish eggs and a few infant apes). SemanticMantis (talk) 22:14, 14 June 2016 (UTC)


 * I removed it. The claim doesn't make sense. Guettarda (talk) 01:58, 15 June 2016 (UTC)